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<p>
Next: <a href="Submodel-Options.html#Submodel-Options" accesskey="n" rel="next">Submodel Options</a>, Previous: <a href="Code-Gen-Options.html#Code-Gen-Options" accesskey="p" rel="prev">Code Gen Options</a>, Up: <a href="Invoking-GCC.html#Invoking-GCC" accesskey="u" rel="up">Invoking GCC</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="GCC-Developer-Options"></a>
<h3 class="section">3.17 GCC Developer Options</h3>
<a name="index-developer-options"></a>
<a name="index-debugging-GCC"></a>
<a name="index-debug-dump-options"></a>
<a name="index-dump-options"></a>
<a name="index-compilation-statistics"></a>

<p>This section describes command-line options that are primarily of
interest to GCC developers, including options to support compiler
testing and investigation of compiler bugs and compile-time
performance problems.  This includes options that produce debug dumps
at various points in the compilation; that print statistics such as
memory use and execution time; and that print information about GCC&rsquo;s
configuration, such as where it searches for libraries.  You should
rarely need to use any of these options for ordinary compilation and
linking tasks.
</p>
<dl compact="compact">
<dt><code>-d<var>letters</var></code></dt>
<dt><code>-fdump-rtl-<var>pass</var></code></dt>
<dt><code>-fdump-rtl-<var>pass</var>=<var>filename</var></code></dt>
<dd><a name="index-d"></a>
<a name="index-fdump_002drtl_002dpass"></a>
<p>Says to make debugging dumps during compilation at times specified by
<var>letters</var>.  This is used for debugging the RTL-based passes of the
compiler.  The file names for most of the dumps are made by appending
a pass number and a word to the <var>dumpname</var>, and the files are
created in the directory of the output file.  In case of
<samp>=<var>filename</var></samp> option, the dump is output on the given file
instead of the pass numbered dump files.  Note that the pass number is
assigned as passes are registered into the pass manager.  Most passes
are registered in the order that they will execute and for these passes
the number corresponds to the pass execution order.  However, passes
registered by plugins, passes specific to compilation targets, or
passes that are otherwise registered after all the other passes are
numbered higher than a pass named &quot;final&quot;, even if they are executed
earlier.  <var>dumpname</var> is generated from the name of the output
file if explicitly specified and not an executable, otherwise it is
the basename of the source file.  These switches may have different
effects when <samp>-E</samp> is used for preprocessing.
</p>
<p>Debug dumps can be enabled with a <samp>-fdump-rtl</samp> switch or some
<samp>-d</samp> option <var>letters</var>.  Here are the possible
letters for use in <var>pass</var> and <var>letters</var>, and their meanings:
</p>
<dl compact="compact">
<dt><code>-fdump-rtl-alignments</code></dt>
<dd><a name="index-fdump_002drtl_002dalignments"></a>
<p>Dump after branch alignments have been computed.
</p>
</dd>
<dt><code>-fdump-rtl-asmcons</code></dt>
<dd><a name="index-fdump_002drtl_002dasmcons"></a>
<p>Dump after fixing rtl statements that have unsatisfied in/out constraints.
</p>
</dd>
<dt><code>-fdump-rtl-auto_inc_dec</code></dt>
<dd><a name="index-fdump_002drtl_002dauto_005finc_005fdec"></a>
<p>Dump after auto-inc-dec discovery.  This pass is only run on
architectures that have auto inc or auto dec instructions.
</p>
</dd>
<dt><code>-fdump-rtl-barriers</code></dt>
<dd><a name="index-fdump_002drtl_002dbarriers"></a>
<p>Dump after cleaning up the barrier instructions.
</p>
</dd>
<dt><code>-fdump-rtl-bbpart</code></dt>
<dd><a name="index-fdump_002drtl_002dbbpart"></a>
<p>Dump after partitioning hot and cold basic blocks.
</p>
</dd>
<dt><code>-fdump-rtl-bbro</code></dt>
<dd><a name="index-fdump_002drtl_002dbbro"></a>
<p>Dump after block reordering.
</p>
</dd>
<dt><code>-fdump-rtl-btl1</code></dt>
<dt><code>-fdump-rtl-btl2</code></dt>
<dd><a name="index-fdump_002drtl_002dbtl2"></a>
<a name="index-fdump_002drtl_002dbtl2-1"></a>
<p><samp>-fdump-rtl-btl1</samp> and <samp>-fdump-rtl-btl2</samp> enable dumping
after the two branch
target load optimization passes.
</p>
</dd>
<dt><code>-fdump-rtl-bypass</code></dt>
<dd><a name="index-fdump_002drtl_002dbypass"></a>
<p>Dump after jump bypassing and control flow optimizations.
</p>
</dd>
<dt><code>-fdump-rtl-combine</code></dt>
<dd><a name="index-fdump_002drtl_002dcombine"></a>
<p>Dump after the RTL instruction combination pass.
</p>
</dd>
<dt><code>-fdump-rtl-compgotos</code></dt>
<dd><a name="index-fdump_002drtl_002dcompgotos"></a>
<p>Dump after duplicating the computed gotos.
</p>
</dd>
<dt><code>-fdump-rtl-ce1</code></dt>
<dt><code>-fdump-rtl-ce2</code></dt>
<dt><code>-fdump-rtl-ce3</code></dt>
<dd><a name="index-fdump_002drtl_002dce1"></a>
<a name="index-fdump_002drtl_002dce2"></a>
<a name="index-fdump_002drtl_002dce3"></a>
<p><samp>-fdump-rtl-ce1</samp>, <samp>-fdump-rtl-ce2</samp>, and
<samp>-fdump-rtl-ce3</samp> enable dumping after the three
if conversion passes.
</p>
</dd>
<dt><code>-fdump-rtl-cprop_hardreg</code></dt>
<dd><a name="index-fdump_002drtl_002dcprop_005fhardreg"></a>
<p>Dump after hard register copy propagation.
</p>
</dd>
<dt><code>-fdump-rtl-csa</code></dt>
<dd><a name="index-fdump_002drtl_002dcsa"></a>
<p>Dump after combining stack adjustments.
</p>
</dd>
<dt><code>-fdump-rtl-cse1</code></dt>
<dt><code>-fdump-rtl-cse2</code></dt>
<dd><a name="index-fdump_002drtl_002dcse1"></a>
<a name="index-fdump_002drtl_002dcse2"></a>
<p><samp>-fdump-rtl-cse1</samp> and <samp>-fdump-rtl-cse2</samp> enable dumping after
the two common subexpression elimination passes.
</p>
</dd>
<dt><code>-fdump-rtl-dce</code></dt>
<dd><a name="index-fdump_002drtl_002ddce"></a>
<p>Dump after the standalone dead code elimination passes.
</p>
</dd>
<dt><code>-fdump-rtl-dbr</code></dt>
<dd><a name="index-fdump_002drtl_002ddbr"></a>
<p>Dump after delayed branch scheduling.
</p>
</dd>
<dt><code>-fdump-rtl-dce1</code></dt>
<dt><code>-fdump-rtl-dce2</code></dt>
<dd><a name="index-fdump_002drtl_002ddce1"></a>
<a name="index-fdump_002drtl_002ddce2"></a>
<p><samp>-fdump-rtl-dce1</samp> and <samp>-fdump-rtl-dce2</samp> enable dumping after
the two dead store elimination passes.
</p>
</dd>
<dt><code>-fdump-rtl-eh</code></dt>
<dd><a name="index-fdump_002drtl_002deh"></a>
<p>Dump after finalization of EH handling code.
</p>
</dd>
<dt><code>-fdump-rtl-eh_ranges</code></dt>
<dd><a name="index-fdump_002drtl_002deh_005franges"></a>
<p>Dump after conversion of EH handling range regions.
</p>
</dd>
<dt><code>-fdump-rtl-expand</code></dt>
<dd><a name="index-fdump_002drtl_002dexpand"></a>
<p>Dump after RTL generation.
</p>
</dd>
<dt><code>-fdump-rtl-fwprop1</code></dt>
<dt><code>-fdump-rtl-fwprop2</code></dt>
<dd><a name="index-fdump_002drtl_002dfwprop1"></a>
<a name="index-fdump_002drtl_002dfwprop2"></a>
<p><samp>-fdump-rtl-fwprop1</samp> and <samp>-fdump-rtl-fwprop2</samp> enable
dumping after the two forward propagation passes.
</p>
</dd>
<dt><code>-fdump-rtl-gcse1</code></dt>
<dt><code>-fdump-rtl-gcse2</code></dt>
<dd><a name="index-fdump_002drtl_002dgcse1"></a>
<a name="index-fdump_002drtl_002dgcse2"></a>
<p><samp>-fdump-rtl-gcse1</samp> and <samp>-fdump-rtl-gcse2</samp> enable dumping
after global common subexpression elimination.
</p>
</dd>
<dt><code>-fdump-rtl-init-regs</code></dt>
<dd><a name="index-fdump_002drtl_002dinit_002dregs"></a>
<p>Dump after the initialization of the registers.
</p>
</dd>
<dt><code>-fdump-rtl-initvals</code></dt>
<dd><a name="index-fdump_002drtl_002dinitvals"></a>
<p>Dump after the computation of the initial value sets.
</p>
</dd>
<dt><code>-fdump-rtl-into_cfglayout</code></dt>
<dd><a name="index-fdump_002drtl_002dinto_005fcfglayout"></a>
<p>Dump after converting to cfglayout mode.
</p>
</dd>
<dt><code>-fdump-rtl-ira</code></dt>
<dd><a name="index-fdump_002drtl_002dira"></a>
<p>Dump after iterated register allocation.
</p>
</dd>
<dt><code>-fdump-rtl-jump</code></dt>
<dd><a name="index-fdump_002drtl_002djump"></a>
<p>Dump after the second jump optimization.
</p>
</dd>
<dt><code>-fdump-rtl-loop2</code></dt>
<dd><a name="index-fdump_002drtl_002dloop2"></a>
<p><samp>-fdump-rtl-loop2</samp> enables dumping after the rtl
loop optimization passes.
</p>
</dd>
<dt><code>-fdump-rtl-mach</code></dt>
<dd><a name="index-fdump_002drtl_002dmach"></a>
<p>Dump after performing the machine dependent reorganization pass, if that
pass exists.
</p>
</dd>
<dt><code>-fdump-rtl-mode_sw</code></dt>
<dd><a name="index-fdump_002drtl_002dmode_005fsw"></a>
<p>Dump after removing redundant mode switches.
</p>
</dd>
<dt><code>-fdump-rtl-rnreg</code></dt>
<dd><a name="index-fdump_002drtl_002drnreg"></a>
<p>Dump after register renumbering.
</p>
</dd>
<dt><code>-fdump-rtl-outof_cfglayout</code></dt>
<dd><a name="index-fdump_002drtl_002doutof_005fcfglayout"></a>
<p>Dump after converting from cfglayout mode.
</p>
</dd>
<dt><code>-fdump-rtl-peephole2</code></dt>
<dd><a name="index-fdump_002drtl_002dpeephole2"></a>
<p>Dump after the peephole pass.
</p>
</dd>
<dt><code>-fdump-rtl-postreload</code></dt>
<dd><a name="index-fdump_002drtl_002dpostreload"></a>
<p>Dump after post-reload optimizations.
</p>
</dd>
<dt><code>-fdump-rtl-pro_and_epilogue</code></dt>
<dd><a name="index-fdump_002drtl_002dpro_005fand_005fepilogue"></a>
<p>Dump after generating the function prologues and epilogues.
</p>
</dd>
<dt><code>-fdump-rtl-sched1</code></dt>
<dt><code>-fdump-rtl-sched2</code></dt>
<dd><a name="index-fdump_002drtl_002dsched1"></a>
<a name="index-fdump_002drtl_002dsched2"></a>
<p><samp>-fdump-rtl-sched1</samp> and <samp>-fdump-rtl-sched2</samp> enable dumping
after the basic block scheduling passes.
</p>
</dd>
<dt><code>-fdump-rtl-ree</code></dt>
<dd><a name="index-fdump_002drtl_002dree"></a>
<p>Dump after sign/zero extension elimination.
</p>
</dd>
<dt><code>-fdump-rtl-seqabstr</code></dt>
<dd><a name="index-fdump_002drtl_002dseqabstr"></a>
<p>Dump after common sequence discovery.
</p>
</dd>
<dt><code>-fdump-rtl-shorten</code></dt>
<dd><a name="index-fdump_002drtl_002dshorten"></a>
<p>Dump after shortening branches.
</p>
</dd>
<dt><code>-fdump-rtl-sibling</code></dt>
<dd><a name="index-fdump_002drtl_002dsibling"></a>
<p>Dump after sibling call optimizations.
</p>
</dd>
<dt><code>-fdump-rtl-split1</code></dt>
<dt><code>-fdump-rtl-split2</code></dt>
<dt><code>-fdump-rtl-split3</code></dt>
<dt><code>-fdump-rtl-split4</code></dt>
<dt><code>-fdump-rtl-split5</code></dt>
<dd><a name="index-fdump_002drtl_002dsplit1"></a>
<a name="index-fdump_002drtl_002dsplit2"></a>
<a name="index-fdump_002drtl_002dsplit3"></a>
<a name="index-fdump_002drtl_002dsplit4"></a>
<a name="index-fdump_002drtl_002dsplit5"></a>
<p>These options enable dumping after five rounds of
instruction splitting.
</p>
</dd>
<dt><code>-fdump-rtl-sms</code></dt>
<dd><a name="index-fdump_002drtl_002dsms"></a>
<p>Dump after modulo scheduling.  This pass is only run on some
architectures.
</p>
</dd>
<dt><code>-fdump-rtl-stack</code></dt>
<dd><a name="index-fdump_002drtl_002dstack"></a>
<p>Dump after conversion from GCC&rsquo;s &ldquo;flat register file&rdquo; registers to the
x87&rsquo;s stack-like registers.  This pass is only run on x86 variants.
</p>
</dd>
<dt><code>-fdump-rtl-subreg1</code></dt>
<dt><code>-fdump-rtl-subreg2</code></dt>
<dd><a name="index-fdump_002drtl_002dsubreg1"></a>
<a name="index-fdump_002drtl_002dsubreg2"></a>
<p><samp>-fdump-rtl-subreg1</samp> and <samp>-fdump-rtl-subreg2</samp> enable dumping after
the two subreg expansion passes.
</p>
</dd>
<dt><code>-fdump-rtl-unshare</code></dt>
<dd><a name="index-fdump_002drtl_002dunshare"></a>
<p>Dump after all rtl has been unshared.
</p>
</dd>
<dt><code>-fdump-rtl-vartrack</code></dt>
<dd><a name="index-fdump_002drtl_002dvartrack"></a>
<p>Dump after variable tracking.
</p>
</dd>
<dt><code>-fdump-rtl-vregs</code></dt>
<dd><a name="index-fdump_002drtl_002dvregs"></a>
<p>Dump after converting virtual registers to hard registers.
</p>
</dd>
<dt><code>-fdump-rtl-web</code></dt>
<dd><a name="index-fdump_002drtl_002dweb"></a>
<p>Dump after live range splitting.
</p>
</dd>
<dt><code>-fdump-rtl-regclass</code></dt>
<dt><code>-fdump-rtl-subregs_of_mode_init</code></dt>
<dt><code>-fdump-rtl-subregs_of_mode_finish</code></dt>
<dt><code>-fdump-rtl-dfinit</code></dt>
<dt><code>-fdump-rtl-dfinish</code></dt>
<dd><a name="index-fdump_002drtl_002dregclass"></a>
<a name="index-fdump_002drtl_002dsubregs_005fof_005fmode_005finit"></a>
<a name="index-fdump_002drtl_002dsubregs_005fof_005fmode_005ffinish"></a>
<a name="index-fdump_002drtl_002ddfinit"></a>
<a name="index-fdump_002drtl_002ddfinish"></a>
<p>These dumps are defined but always produce empty files.
</p>
</dd>
<dt><code>-da</code></dt>
<dt><code>-fdump-rtl-all</code></dt>
<dd><a name="index-da"></a>
<a name="index-fdump_002drtl_002dall"></a>
<p>Produce all the dumps listed above.
</p>
</dd>
<dt><code>-dA</code></dt>
<dd><a name="index-dA"></a>
<p>Annotate the assembler output with miscellaneous debugging information.
</p>
</dd>
<dt><code>-dD</code></dt>
<dd><a name="index-dD-1"></a>
<p>Dump all macro definitions, at the end of preprocessing, in addition to
normal output.
</p>
</dd>
<dt><code>-dH</code></dt>
<dd><a name="index-dH"></a>
<p>Produce a core dump whenever an error occurs.
</p>
</dd>
<dt><code>-dp</code></dt>
<dd><a name="index-dp"></a>
<p>Annotate the assembler output with a comment indicating which
pattern and alternative is used.  The length of each instruction is
also printed.
</p>
</dd>
<dt><code>-dP</code></dt>
<dd><a name="index-dP"></a>
<p>Dump the RTL in the assembler output as a comment before each instruction.
Also turns on <samp>-dp</samp> annotation.
</p>
</dd>
<dt><code>-dx</code></dt>
<dd><a name="index-dx"></a>
<p>Just generate RTL for a function instead of compiling it.  Usually used
with <samp>-fdump-rtl-expand</samp>.
</p></dd>
</dl>

</dd>
<dt><code>-fdump-noaddr</code></dt>
<dd><a name="index-fdump_002dnoaddr"></a>
<p>When doing debugging dumps, suppress address output.  This makes it more
feasible to use diff on debugging dumps for compiler invocations with
different compiler binaries and/or different
text / bss / data / heap / stack / dso start locations.
</p>
</dd>
<dt><code>-freport-bug</code></dt>
<dd><a name="index-freport_002dbug"></a>
<p>Collect and dump debug information into a temporary file if an
internal compiler error (ICE) occurs.
</p>
</dd>
<dt><code>-fdump-unnumbered</code></dt>
<dd><a name="index-fdump_002dunnumbered"></a>
<p>When doing debugging dumps, suppress instruction numbers and address output.
This makes it more feasible to use diff on debugging dumps for compiler
invocations with different options, in particular with and without
<samp>-g</samp>.
</p>
</dd>
<dt><code>-fdump-unnumbered-links</code></dt>
<dd><a name="index-fdump_002dunnumbered_002dlinks"></a>
<p>When doing debugging dumps (see <samp>-d</samp> option above), suppress
instruction numbers for the links to the previous and next instructions
in a sequence.
</p>
</dd>
<dt><code>-fdump-translation-unit <span class="roman">(C++ only)</span></code></dt>
<dt><code>-fdump-translation-unit-<var>options</var> <span class="roman">(C++ only)</span></code></dt>
<dd><a name="index-fdump_002dtranslation_002dunit"></a>
<p>Dump a representation of the tree structure for the entire translation
unit to a file.  The file name is made by appending <samp>.tu</samp> to the
source file name, and the file is created in the same directory as the
output file.  If the &lsquo;<samp>-<var>options</var></samp>&rsquo; form is used, <var>options</var>
controls the details of the dump as described for the
<samp>-fdump-tree</samp> options.
</p>
</dd>
<dt><code>-fdump-class-hierarchy <span class="roman">(C++ only)</span></code></dt>
<dt><code>-fdump-class-hierarchy-<var>options</var> <span class="roman">(C++ only)</span></code></dt>
<dd><a name="index-fdump_002dclass_002dhierarchy"></a>
<p>Dump a representation of each class&rsquo;s hierarchy and virtual function
table layout to a file.  The file name is made by appending
<samp>.class</samp> to the source file name, and the file is created in the
same directory as the output file.  If the &lsquo;<samp>-<var>options</var></samp>&rsquo; form
is used, <var>options</var> controls the details of the dump as described
for the <samp>-fdump-tree</samp> options.
</p>
</dd>
<dt><code>-fdump-ipa-<var>switch</var></code></dt>
<dd><a name="index-fdump_002dipa"></a>
<p>Control the dumping at various stages of inter-procedural analysis
language tree to a file.  The file name is generated by appending a
switch specific suffix to the source file name, and the file is created
in the same directory as the output file.  The following dumps are
possible:
</p>
<dl compact="compact">
<dt>&lsquo;<samp>all</samp>&rsquo;</dt>
<dd><p>Enables all inter-procedural analysis dumps.
</p>
</dd>
<dt>&lsquo;<samp>cgraph</samp>&rsquo;</dt>
<dd><p>Dumps information about call-graph optimization, unused function removal,
and inlining decisions.
</p>
</dd>
<dt>&lsquo;<samp>inline</samp>&rsquo;</dt>
<dd><p>Dump after function inlining.
</p>
</dd>
</dl>

</dd>
<dt><code>-fdump-passes</code></dt>
<dd><a name="index-fdump_002dpasses"></a>
<p>Dump the list of optimization passes that are turned on and off by
the current command-line options.
</p>
</dd>
<dt><code>-fdump-statistics-<var>option</var></code></dt>
<dd><a name="index-fdump_002dstatistics"></a>
<p>Enable and control dumping of pass statistics in a separate file.  The
file name is generated by appending a suffix ending in
&lsquo;<samp>.statistics</samp>&rsquo; to the source file name, and the file is created in
the same directory as the output file.  If the &lsquo;<samp>-<var>option</var></samp>&rsquo;
form is used, &lsquo;<samp>-stats</samp>&rsquo; causes counters to be summed over the
whole compilation unit while &lsquo;<samp>-details</samp>&rsquo; dumps every event as
the passes generate them.  The default with no option is to sum
counters for each function compiled.
</p>
</dd>
<dt><code>-fdump-tree-<var>switch</var></code></dt>
<dt><code>-fdump-tree-<var>switch</var>-<var>options</var></code></dt>
<dt><code>-fdump-tree-<var>switch</var>-<var>options</var>=<var>filename</var></code></dt>
<dd><a name="index-fdump_002dtree"></a>
<p>Control the dumping at various stages of processing the intermediate
language tree to a file.  The file name is generated by appending a
switch-specific suffix to the source file name, and the file is
created in the same directory as the output file. In case of
<samp>=<var>filename</var></samp> option, the dump is output on the given file
instead of the auto named dump files.  If the &lsquo;<samp>-<var>options</var></samp>&rsquo;
form is used, <var>options</var> is a list of &lsquo;<samp>-</samp>&rsquo; separated options
which control the details of the dump.  Not all options are applicable
to all dumps; those that are not meaningful are ignored.  The
following options are available
</p>
<dl compact="compact">
<dt>&lsquo;<samp>address</samp>&rsquo;</dt>
<dd><p>Print the address of each node.  Usually this is not meaningful as it
changes according to the environment and source file.  Its primary use
is for tying up a dump file with a debug environment.
</p></dd>
<dt>&lsquo;<samp>asmname</samp>&rsquo;</dt>
<dd><p>If <code>DECL_ASSEMBLER_NAME</code> has been set for a given decl, use that
in the dump instead of <code>DECL_NAME</code>.  Its primary use is ease of
use working backward from mangled names in the assembly file.
</p></dd>
<dt>&lsquo;<samp>slim</samp>&rsquo;</dt>
<dd><p>When dumping front-end intermediate representations, inhibit dumping
of members of a scope or body of a function merely because that scope
has been reached.  Only dump such items when they are directly reachable
by some other path.
</p>
<p>When dumping pretty-printed trees, this option inhibits dumping the
bodies of control structures.
</p>
<p>When dumping RTL, print the RTL in slim (condensed) form instead of
the default LISP-like representation.
</p></dd>
<dt>&lsquo;<samp>raw</samp>&rsquo;</dt>
<dd><p>Print a raw representation of the tree.  By default, trees are
pretty-printed into a C-like representation.
</p></dd>
<dt>&lsquo;<samp>details</samp>&rsquo;</dt>
<dd><p>Enable more detailed dumps (not honored by every dump option). Also
include information from the optimization passes.
</p></dd>
<dt>&lsquo;<samp>stats</samp>&rsquo;</dt>
<dd><p>Enable dumping various statistics about the pass (not honored by every dump
option).
</p></dd>
<dt>&lsquo;<samp>blocks</samp>&rsquo;</dt>
<dd><p>Enable showing basic block boundaries (disabled in raw dumps).
</p></dd>
<dt>&lsquo;<samp>graph</samp>&rsquo;</dt>
<dd><p>For each of the other indicated dump files (<samp>-fdump-rtl-<var>pass</var></samp>),
dump a representation of the control flow graph suitable for viewing with
GraphViz to <samp><var>file</var>.<var>passid</var>.<var>pass</var>.dot</samp>.  Each function in
the file is pretty-printed as a subgraph, so that GraphViz can render them
all in a single plot.
</p>
<p>This option currently only works for RTL dumps, and the RTL is always
dumped in slim form.
</p></dd>
<dt>&lsquo;<samp>vops</samp>&rsquo;</dt>
<dd><p>Enable showing virtual operands for every statement.
</p></dd>
<dt>&lsquo;<samp>lineno</samp>&rsquo;</dt>
<dd><p>Enable showing line numbers for statements.
</p></dd>
<dt>&lsquo;<samp>uid</samp>&rsquo;</dt>
<dd><p>Enable showing the unique ID (<code>DECL_UID</code>) for each variable.
</p></dd>
<dt>&lsquo;<samp>verbose</samp>&rsquo;</dt>
<dd><p>Enable showing the tree dump for each statement.
</p></dd>
<dt>&lsquo;<samp>eh</samp>&rsquo;</dt>
<dd><p>Enable showing the EH region number holding each statement.
</p></dd>
<dt>&lsquo;<samp>scev</samp>&rsquo;</dt>
<dd><p>Enable showing scalar evolution analysis details.
</p></dd>
<dt>&lsquo;<samp>optimized</samp>&rsquo;</dt>
<dd><p>Enable showing optimization information (only available in certain
passes).
</p></dd>
<dt>&lsquo;<samp>missed</samp>&rsquo;</dt>
<dd><p>Enable showing missed optimization information (only available in certain
passes).
</p></dd>
<dt>&lsquo;<samp>note</samp>&rsquo;</dt>
<dd><p>Enable other detailed optimization information (only available in
certain passes).
</p></dd>
<dt>&lsquo;<samp>=<var>filename</var></samp>&rsquo;</dt>
<dd><p>Instead of an auto named dump file, output into the given file
name. The file names <samp>stdout</samp> and <samp>stderr</samp> are treated
specially and are considered already open standard streams. For
example,
</p>
<div class="smallexample">
<pre class="smallexample">gcc -O2 -ftree-vectorize -fdump-tree-vect-blocks=foo.dump
     -fdump-tree-pre=stderr file.c
</pre></div>

<p>outputs vectorizer dump into <samp>foo.dump</samp>, while the PRE dump is
output on to <samp>stderr</samp>. If two conflicting dump filenames are
given for the same pass, then the latter option overrides the earlier
one.
</p>
</dd>
<dt>&lsquo;<samp>split-paths</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dsplit_002dpaths"></a>
<p>Dump each function after splitting paths to loop backedges.  The file
name is made by appending <samp>.split-paths</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>all</samp>&rsquo;</dt>
<dd><p>Turn on all options, except <samp>raw</samp>, <samp>slim</samp>, <samp>verbose</samp>
and <samp>lineno</samp>.
</p>
</dd>
<dt>&lsquo;<samp>optall</samp>&rsquo;</dt>
<dd><p>Turn on all optimization options, i.e., <samp>optimized</samp>,
<samp>missed</samp>, and <samp>note</samp>.
</p></dd>
</dl>

<p>The following tree dumps are possible:
</p><dl compact="compact">
<dt>&lsquo;<samp>original</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002doriginal"></a>
<p>Dump before any tree based optimization, to <samp><var>file</var>.original</samp>.
</p>
</dd>
<dt>&lsquo;<samp>optimized</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002doptimized"></a>
<p>Dump after all tree based optimization, to <samp><var>file</var>.optimized</samp>.
</p>
</dd>
<dt>&lsquo;<samp>gimple</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dgimple"></a>
<p>Dump each function before and after the gimplification pass to a file.  The
file name is made by appending <samp>.gimple</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>cfg</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dcfg"></a>
<p>Dump the control flow graph of each function to a file.  The file name is
made by appending <samp>.cfg</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>ch</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dch"></a>
<p>Dump each function after copying loop headers.  The file name is made by
appending <samp>.ch</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>ssa</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dssa"></a>
<p>Dump SSA related information to a file.  The file name is made by appending
<samp>.ssa</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>alias</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dalias"></a>
<p>Dump aliasing information for each function.  The file name is made by
appending <samp>.alias</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>ccp</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dccp"></a>
<p>Dump each function after CCP.  The file name is made by appending
<samp>.ccp</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>storeccp</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dstoreccp"></a>
<p>Dump each function after STORE-CCP.  The file name is made by appending
<samp>.storeccp</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>pre</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dpre"></a>
<p>Dump trees after partial redundancy elimination.  The file name is made
by appending <samp>.pre</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>fre</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dfre"></a>
<p>Dump trees after full redundancy elimination.  The file name is made
by appending <samp>.fre</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>copyprop</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dcopyprop"></a>
<p>Dump trees after copy propagation.  The file name is made
by appending <samp>.copyprop</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>store_copyprop</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dstore_005fcopyprop"></a>
<p>Dump trees after store copy-propagation.  The file name is made
by appending <samp>.store_copyprop</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>dce</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002ddce"></a>
<p>Dump each function after dead code elimination.  The file name is made by
appending <samp>.dce</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>sra</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dsra"></a>
<p>Dump each function after performing scalar replacement of aggregates.  The
file name is made by appending <samp>.sra</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>sink</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dsink"></a>
<p>Dump each function after performing code sinking.  The file name is made
by appending <samp>.sink</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>dom</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002ddom"></a>
<p>Dump each function after applying dominator tree optimizations.  The file
name is made by appending <samp>.dom</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>dse</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002ddse"></a>
<p>Dump each function after applying dead store elimination.  The file
name is made by appending <samp>.dse</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>phiopt</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dphiopt"></a>
<p>Dump each function after optimizing PHI nodes into straightline code.  The file
name is made by appending <samp>.phiopt</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>backprop</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dbackprop"></a>
<p>Dump each function after back-propagating use information up the definition
chain.  The file name is made by appending <samp>.backprop</samp> to the
source file name.
</p>
</dd>
<dt>&lsquo;<samp>forwprop</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dforwprop"></a>
<p>Dump each function after forward propagating single use variables.  The file
name is made by appending <samp>.forwprop</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>nrv</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dnrv"></a>
<p>Dump each function after applying the named return value optimization on
generic trees.  The file name is made by appending <samp>.nrv</samp> to the source
file name.
</p>
</dd>
<dt>&lsquo;<samp>vect</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dvect"></a>
<p>Dump each function after applying vectorization of loops.  The file name is
made by appending <samp>.vect</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>slp</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dslp"></a>
<p>Dump each function after applying vectorization of basic blocks.  The file name
is made by appending <samp>.slp</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>vrp</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dvrp"></a>
<p>Dump each function after Value Range Propagation (VRP).  The file name
is made by appending <samp>.vrp</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>oaccdevlow</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002doaccdevlow"></a>
<p>Dump each function after applying device-specific OpenACC transformations.
The file name is made by appending <samp>.oaccdevlow</samp> to the source file name.
</p>
</dd>
<dt>&lsquo;<samp>all</samp>&rsquo;</dt>
<dd><a name="index-fdump_002dtree_002dall"></a>
<p>Enable all the available tree dumps with the flags provided in this option.
</p></dd>
</dl>

</dd>
<dt><code>-fopt-info</code></dt>
<dt><code>-fopt-info-<var>options</var></code></dt>
<dt><code>-fopt-info-<var>options</var>=<var>filename</var></code></dt>
<dd><a name="index-fopt_002dinfo"></a>
<p>Controls optimization dumps from various optimization passes. If the
&lsquo;<samp>-<var>options</var></samp>&rsquo; form is used, <var>options</var> is a list of
&lsquo;<samp>-</samp>&rsquo; separated option keywords to select the dump details and
optimizations.  
</p>
<p>The <var>options</var> can be divided into two groups: options describing the
verbosity of the dump, and options describing which optimizations
should be included. The options from both the groups can be freely
mixed as they are non-overlapping. However, in case of any conflicts,
the later options override the earlier options on the command
line. 
</p>
<p>The following options control the dump verbosity:
</p>
<dl compact="compact">
<dt>&lsquo;<samp>optimized</samp>&rsquo;</dt>
<dd><p>Print information when an optimization is successfully applied. It is
up to a pass to decide which information is relevant. For example, the
vectorizer passes print the source location of loops which are
successfully vectorized.
</p></dd>
<dt>&lsquo;<samp>missed</samp>&rsquo;</dt>
<dd><p>Print information about missed optimizations. Individual passes
control which information to include in the output. 
</p></dd>
<dt>&lsquo;<samp>note</samp>&rsquo;</dt>
<dd><p>Print verbose information about optimizations, such as certain
transformations, more detailed messages about decisions etc.
</p></dd>
<dt>&lsquo;<samp>all</samp>&rsquo;</dt>
<dd><p>Print detailed optimization information. This includes
&lsquo;<samp>optimized</samp>&rsquo;, &lsquo;<samp>missed</samp>&rsquo;, and &lsquo;<samp>note</samp>&rsquo;.
</p></dd>
</dl>

<p>One or more of the following option keywords can be used to describe a
group of optimizations:
</p>
<dl compact="compact">
<dt>&lsquo;<samp>ipa</samp>&rsquo;</dt>
<dd><p>Enable dumps from all interprocedural optimizations.
</p></dd>
<dt>&lsquo;<samp>loop</samp>&rsquo;</dt>
<dd><p>Enable dumps from all loop optimizations.
</p></dd>
<dt>&lsquo;<samp>inline</samp>&rsquo;</dt>
<dd><p>Enable dumps from all inlining optimizations.
</p></dd>
<dt>&lsquo;<samp>vec</samp>&rsquo;</dt>
<dd><p>Enable dumps from all vectorization optimizations.
</p></dd>
<dt>&lsquo;<samp>optall</samp>&rsquo;</dt>
<dd><p>Enable dumps from all optimizations. This is a superset of
the optimization groups listed above.
</p></dd>
</dl>

<p>If <var>options</var> is
omitted, it defaults to &lsquo;<samp>optimized-optall</samp>&rsquo;, which means to dump all
info about successful optimizations from all the passes.  
</p>
<p>If the <var>filename</var> is provided, then the dumps from all the
applicable optimizations are concatenated into the <var>filename</var>.
Otherwise the dump is output onto <samp>stderr</samp>. Though multiple
<samp>-fopt-info</samp> options are accepted, only one of them can include
a <var>filename</var>. If other filenames are provided then all but the
first such option are ignored.
</p>
<p>Note that the output <var>filename</var> is overwritten
in case of multiple translation units. If a combined output from
multiple translation units is desired, <samp>stderr</samp> should be used
instead.
</p>
<p>In the following example, the optimization info is output to
<samp>stderr</samp>:
</p>
<div class="smallexample">
<pre class="smallexample">gcc -O3 -fopt-info
</pre></div>

<p>This example:
</p><div class="smallexample">
<pre class="smallexample">gcc -O3 -fopt-info-missed=missed.all
</pre></div>

<p>outputs missed optimization report from all the passes into
<samp>missed.all</samp>, and this one:
</p>
<div class="smallexample">
<pre class="smallexample">gcc -O2 -ftree-vectorize -fopt-info-vec-missed
</pre></div>

<p>prints information about missed optimization opportunities from
vectorization passes on <samp>stderr</samp>.  
Note that <samp>-fopt-info-vec-missed</samp> is equivalent to 
<samp>-fopt-info-missed-vec</samp>.
</p>
<p>As another example,
</p><div class="smallexample">
<pre class="smallexample">gcc -O3 -fopt-info-inline-optimized-missed=inline.txt
</pre></div>

<p>outputs information about missed optimizations as well as
optimized locations from all the inlining passes into
<samp>inline.txt</samp>.
</p>
<p>Finally, consider:
</p>
<div class="smallexample">
<pre class="smallexample">gcc -fopt-info-vec-missed=vec.miss -fopt-info-loop-optimized=loop.opt
</pre></div>

<p>Here the two output filenames <samp>vec.miss</samp> and <samp>loop.opt</samp> are
in conflict since only one output file is allowed. In this case, only
the first option takes effect and the subsequent options are
ignored. Thus only <samp>vec.miss</samp> is produced which contains
dumps from the vectorizer about missed opportunities.
</p>
</dd>
<dt><code>-fsched-verbose=<var>n</var></code></dt>
<dd><a name="index-fsched_002dverbose"></a>
<p>On targets that use instruction scheduling, this option controls the
amount of debugging output the scheduler prints to the dump files.
</p>
<p>For <var>n</var> greater than zero, <samp>-fsched-verbose</samp> outputs the
same information as <samp>-fdump-rtl-sched1</samp> and <samp>-fdump-rtl-sched2</samp>.
For <var>n</var> greater than one, it also output basic block probabilities,
detailed ready list information and unit/insn info.  For <var>n</var> greater
than two, it includes RTL at abort point, control-flow and regions info.
And for <var>n</var> over four, <samp>-fsched-verbose</samp> also includes
dependence info.
</p>


</dd>
<dt><code>-fenable-<var>kind</var>-<var>pass</var></code></dt>
<dt><code>-fdisable-<var>kind</var>-<var>pass</var>=<var>range-list</var></code></dt>
<dd><a name="index-fdisable_002d"></a>
<a name="index-fenable_002d"></a>

<p>This is a set of options that are used to explicitly disable/enable
optimization passes.  These options are intended for use for debugging GCC.
Compiler users should use regular options for enabling/disabling
passes instead.
</p>
<dl compact="compact">
<dt><code>-fdisable-ipa-<var>pass</var></code></dt>
<dd><p>Disable IPA pass <var>pass</var>. <var>pass</var> is the pass name.  If the same pass is
statically invoked in the compiler multiple times, the pass name should be
appended with a sequential number starting from 1.
</p>
</dd>
<dt><code>-fdisable-rtl-<var>pass</var></code></dt>
<dt><code>-fdisable-rtl-<var>pass</var>=<var>range-list</var></code></dt>
<dd><p>Disable RTL pass <var>pass</var>.  <var>pass</var> is the pass name.  If the same pass is
statically invoked in the compiler multiple times, the pass name should be
appended with a sequential number starting from 1.  <var>range-list</var> is a 
comma-separated list of function ranges or assembler names.  Each range is a number
pair separated by a colon.  The range is inclusive in both ends.  If the range
is trivial, the number pair can be simplified as a single number.  If the
function&rsquo;s call graph node&rsquo;s <var>uid</var> falls within one of the specified ranges,
the <var>pass</var> is disabled for that function.  The <var>uid</var> is shown in the
function header of a dump file, and the pass names can be dumped by using
option <samp>-fdump-passes</samp>.
</p>
</dd>
<dt><code>-fdisable-tree-<var>pass</var></code></dt>
<dt><code>-fdisable-tree-<var>pass</var>=<var>range-list</var></code></dt>
<dd><p>Disable tree pass <var>pass</var>.  See <samp>-fdisable-rtl</samp> for the description of
option arguments.
</p>
</dd>
<dt><code>-fenable-ipa-<var>pass</var></code></dt>
<dd><p>Enable IPA pass <var>pass</var>.  <var>pass</var> is the pass name.  If the same pass is
statically invoked in the compiler multiple times, the pass name should be
appended with a sequential number starting from 1.
</p>
</dd>
<dt><code>-fenable-rtl-<var>pass</var></code></dt>
<dt><code>-fenable-rtl-<var>pass</var>=<var>range-list</var></code></dt>
<dd><p>Enable RTL pass <var>pass</var>.  See <samp>-fdisable-rtl</samp> for option argument
description and examples.
</p>
</dd>
<dt><code>-fenable-tree-<var>pass</var></code></dt>
<dt><code>-fenable-tree-<var>pass</var>=<var>range-list</var></code></dt>
<dd><p>Enable tree pass <var>pass</var>.  See <samp>-fdisable-rtl</samp> for the description
of option arguments.
</p>
</dd>
</dl>

<p>Here are some examples showing uses of these options.
</p>
<div class="smallexample">
<pre class="smallexample">
# disable ccp1 for all functions
   -fdisable-tree-ccp1
# disable complete unroll for function whose cgraph node uid is 1
   -fenable-tree-cunroll=1
# disable gcse2 for functions at the following ranges [1,1],
# [300,400], and [400,1000]
# disable gcse2 for functions foo and foo2
   -fdisable-rtl-gcse2=foo,foo2
# disable early inlining
   -fdisable-tree-einline
# disable ipa inlining
   -fdisable-ipa-inline
# enable tree full unroll
   -fenable-tree-unroll

</pre></div>

</dd>
<dt><code>-fchecking</code></dt>
<dd><a name="index-fchecking"></a>
<a name="index-fno_002dchecking"></a>
<p>Enable internal consistency checking.  The default depends on
the compiler configuration.
</p>
</dd>
<dt><code>-frandom-seed=<var>string</var></code></dt>
<dd><a name="index-frandom_002dseed"></a>
<p>This option provides a seed that GCC uses in place of
random numbers in generating certain symbol names
that have to be different in every compiled file.  It is also used to
place unique stamps in coverage data files and the object files that
produce them.  You can use the <samp>-frandom-seed</samp> option to produce
reproducibly identical object files.
</p>
<p>The <var>string</var> can either be a number (decimal, octal or hex) or an
arbitrary string (in which case it&rsquo;s converted to a number by
computing CRC32).
</p>
<p>The <var>string</var> should be different for every file you compile.
</p>
</dd>
<dt><code>-save-temps</code></dt>
<dt><code>-save-temps=cwd</code></dt>
<dd><a name="index-save_002dtemps"></a>
<p>Store the usual &ldquo;temporary&rdquo; intermediate files permanently; place them
in the current directory and name them based on the source file.  Thus,
compiling <samp>foo.c</samp> with <samp>-c -save-temps</samp> produces files
<samp>foo.i</samp> and <samp>foo.s</samp>, as well as <samp>foo.o</samp>.  This creates a
preprocessed <samp>foo.i</samp> output file even though the compiler now
normally uses an integrated preprocessor.
</p>
<p>When used in combination with the <samp>-x</samp> command-line option,
<samp>-save-temps</samp> is sensible enough to avoid over writing an
input source file with the same extension as an intermediate file.
The corresponding intermediate file may be obtained by renaming the
source file before using <samp>-save-temps</samp>.
</p>
<p>If you invoke GCC in parallel, compiling several different source
files that share a common base name in different subdirectories or the
same source file compiled for multiple output destinations, it is
likely that the different parallel compilers will interfere with each
other, and overwrite the temporary files.  For instance:
</p>
<div class="smallexample">
<pre class="smallexample">gcc -save-temps -o outdir1/foo.o indir1/foo.c&amp;
gcc -save-temps -o outdir2/foo.o indir2/foo.c&amp;
</pre></div>

<p>may result in <samp>foo.i</samp> and <samp>foo.o</samp> being written to
simultaneously by both compilers.
</p>
</dd>
<dt><code>-save-temps=obj</code></dt>
<dd><a name="index-save_002dtemps_003dobj"></a>
<p>Store the usual &ldquo;temporary&rdquo; intermediate files permanently.  If the
<samp>-o</samp> option is used, the temporary files are based on the
object file.  If the <samp>-o</samp> option is not used, the
<samp>-save-temps=obj</samp> switch behaves like <samp>-save-temps</samp>.
</p>
<p>For example:
</p>
<div class="smallexample">
<pre class="smallexample">gcc -save-temps=obj -c foo.c
gcc -save-temps=obj -c bar.c -o dir/xbar.o
gcc -save-temps=obj foobar.c -o dir2/yfoobar
</pre></div>

<p>creates <samp>foo.i</samp>, <samp>foo.s</samp>, <samp>dir/xbar.i</samp>,
<samp>dir/xbar.s</samp>, <samp>dir2/yfoobar.i</samp>, <samp>dir2/yfoobar.s</samp>, and
<samp>dir2/yfoobar.o</samp>.
</p>
</dd>
<dt><code>-time<span class="roman">[</span>=<var>file</var><span class="roman">]</span></code></dt>
<dd><a name="index-time"></a>
<p>Report the CPU time taken by each subprocess in the compilation
sequence.  For C source files, this is the compiler proper and assembler
(plus the linker if linking is done).
</p>
<p>Without the specification of an output file, the output looks like this:
</p>
<div class="smallexample">
<pre class="smallexample"># cc1 0.12 0.01
# as 0.00 0.01
</pre></div>

<p>The first number on each line is the &ldquo;user time&rdquo;, that is time spent
executing the program itself.  The second number is &ldquo;system time&rdquo;,
time spent executing operating system routines on behalf of the program.
Both numbers are in seconds.
</p>
<p>With the specification of an output file, the output is appended to the
named file, and it looks like this:
</p>
<div class="smallexample">
<pre class="smallexample">0.12 0.01 cc1 <var>options</var>
0.00 0.01 as <var>options</var>
</pre></div>

<p>The &ldquo;user time&rdquo; and the &ldquo;system time&rdquo; are moved before the program
name, and the options passed to the program are displayed, so that one
can later tell what file was being compiled, and with which options.
</p>
</dd>
<dt><code>-fdump-final-insns<span class="roman">[</span>=<var>file</var><span class="roman">]</span></code></dt>
<dd><a name="index-fdump_002dfinal_002dinsns"></a>
<p>Dump the final internal representation (RTL) to <var>file</var>.  If the
optional argument is omitted (or if <var>file</var> is <code>.</code>), the name
of the dump file is determined by appending <code>.gkd</code> to the
compilation output file name.
</p>
</dd>
<dt><code>-fcompare-debug<span class="roman">[</span>=<var>opts</var><span class="roman">]</span></code></dt>
<dd><a name="index-fcompare_002ddebug"></a>
<a name="index-fno_002dcompare_002ddebug"></a>
<p>If no error occurs during compilation, run the compiler a second time,
adding <var>opts</var> and <samp>-fcompare-debug-second</samp> to the arguments
passed to the second compilation.  Dump the final internal
representation in both compilations, and print an error if they differ.
</p>
<p>If the equal sign is omitted, the default <samp>-gtoggle</samp> is used.
</p>
<p>The environment variable <code>GCC_COMPARE_DEBUG</code>, if defined, non-empty
and nonzero, implicitly enables <samp>-fcompare-debug</samp>.  If
<code>GCC_COMPARE_DEBUG</code> is defined to a string starting with a dash,
then it is used for <var>opts</var>, otherwise the default <samp>-gtoggle</samp>
is used.
</p>
<p><samp>-fcompare-debug=</samp>, with the equal sign but without <var>opts</var>,
is equivalent to <samp>-fno-compare-debug</samp>, which disables the dumping
of the final representation and the second compilation, preventing even
<code>GCC_COMPARE_DEBUG</code> from taking effect.
</p>
<p>To verify full coverage during <samp>-fcompare-debug</samp> testing, set
<code>GCC_COMPARE_DEBUG</code> to say <samp>-fcompare-debug-not-overridden</samp>,
which GCC rejects as an invalid option in any actual compilation
(rather than preprocessing, assembly or linking).  To get just a
warning, setting <code>GCC_COMPARE_DEBUG</code> to &lsquo;<samp>-w%n-fcompare-debug
not overridden</samp>&rsquo; will do.
</p>
</dd>
<dt><code>-fcompare-debug-second</code></dt>
<dd><a name="index-fcompare_002ddebug_002dsecond"></a>
<p>This option is implicitly passed to the compiler for the second
compilation requested by <samp>-fcompare-debug</samp>, along with options to
silence warnings, and omitting other options that would cause
side-effect compiler outputs to files or to the standard output.  Dump
files and preserved temporary files are renamed so as to contain the
<code>.gk</code> additional extension during the second compilation, to avoid
overwriting those generated by the first.
</p>
<p>When this option is passed to the compiler driver, it causes the
<em>first</em> compilation to be skipped, which makes it useful for little
other than debugging the compiler proper.
</p>
</dd>
<dt><code>-gtoggle</code></dt>
<dd><a name="index-gtoggle"></a>
<p>Turn off generation of debug info, if leaving out this option
generates it, or turn it on at level 2 otherwise.  The position of this
argument in the command line does not matter; it takes effect after all
other options are processed, and it does so only once, no matter how
many times it is given.  This is mainly intended to be used with
<samp>-fcompare-debug</samp>.
</p>
</dd>
<dt><code>-fvar-tracking-assignments-toggle</code></dt>
<dd><a name="index-fvar_002dtracking_002dassignments_002dtoggle"></a>
<a name="index-fno_002dvar_002dtracking_002dassignments_002dtoggle"></a>
<p>Toggle <samp>-fvar-tracking-assignments</samp>, in the same way that
<samp>-gtoggle</samp> toggles <samp>-g</samp>.
</p>
</dd>
<dt><code>-Q</code></dt>
<dd><a name="index-Q"></a>
<p>Makes the compiler print out each function name as it is compiled, and
print some statistics about each pass when it finishes.
</p>
</dd>
<dt><code>-ftime-report</code></dt>
<dd><a name="index-ftime_002dreport"></a>
<p>Makes the compiler print some statistics about the time consumed by each
pass when it finishes.
</p>
</dd>
<dt><code>-fira-verbose=<var>n</var></code></dt>
<dd><a name="index-fira_002dverbose"></a>
<p>Control the verbosity of the dump file for the integrated register allocator.
The default value is 5.  If the value <var>n</var> is greater or equal to 10,
the dump output is sent to stderr using the same format as <var>n</var> minus 10.
</p>
</dd>
<dt><code>-flto-report</code></dt>
<dd><a name="index-flto_002dreport"></a>
<p>Prints a report with internal details on the workings of the link-time
optimizer.  The contents of this report vary from version to version.
It is meant to be useful to GCC developers when processing object
files in LTO mode (via <samp>-flto</samp>).
</p>
<p>Disabled by default.
</p>
</dd>
<dt><code>-flto-report-wpa</code></dt>
<dd><a name="index-flto_002dreport_002dwpa"></a>
<p>Like <samp>-flto-report</samp>, but only print for the WPA phase of Link
Time Optimization.
</p>
</dd>
<dt><code>-fmem-report</code></dt>
<dd><a name="index-fmem_002dreport"></a>
<p>Makes the compiler print some statistics about permanent memory
allocation when it finishes.
</p>
</dd>
<dt><code>-fmem-report-wpa</code></dt>
<dd><a name="index-fmem_002dreport_002dwpa"></a>
<p>Makes the compiler print some statistics about permanent memory
allocation for the WPA phase only.
</p>
</dd>
<dt><code>-fpre-ipa-mem-report</code></dt>
<dd><a name="index-fpre_002dipa_002dmem_002dreport"></a>
</dd>
<dt><code>-fpost-ipa-mem-report</code></dt>
<dd><a name="index-fpost_002dipa_002dmem_002dreport"></a>
<p>Makes the compiler print some statistics about permanent memory
allocation before or after interprocedural optimization.
</p>
</dd>
<dt><code>-fprofile-report</code></dt>
<dd><a name="index-fprofile_002dreport"></a>
<p>Makes the compiler print some statistics about consistency of the
(estimated) profile and effect of individual passes.
</p>
</dd>
<dt><code>-fstack-usage</code></dt>
<dd><a name="index-fstack_002dusage"></a>
<p>Makes the compiler output stack usage information for the program, on a
per-function basis.  The filename for the dump is made by appending
<samp>.su</samp> to the <var>auxname</var>.  <var>auxname</var> is generated from the name of
the output file, if explicitly specified and it is not an executable,
otherwise it is the basename of the source file.  An entry is made up
of three fields:
</p>
<ul>
<li> The name of the function.
</li><li> A number of bytes.
</li><li> One or more qualifiers: <code>static</code>, <code>dynamic</code>, <code>bounded</code>.
</li></ul>

<p>The qualifier <code>static</code> means that the function manipulates the stack
statically: a fixed number of bytes are allocated for the frame on function
entry and released on function exit; no stack adjustments are otherwise made
in the function.  The second field is this fixed number of bytes.
</p>
<p>The qualifier <code>dynamic</code> means that the function manipulates the stack
dynamically: in addition to the static allocation described above, stack
adjustments are made in the body of the function, for example to push/pop
arguments around function calls.  If the qualifier <code>bounded</code> is also
present, the amount of these adjustments is bounded at compile time and
the second field is an upper bound of the total amount of stack used by
the function.  If it is not present, the amount of these adjustments is
not bounded at compile time and the second field only represents the
bounded part.
</p>
</dd>
<dt><code>-fstats</code></dt>
<dd><a name="index-fstats"></a>
<p>Emit statistics about front-end processing at the end of the compilation.
This option is supported only by the C++ front end, and
the information is generally only useful to the G++ development team.
</p>
</dd>
<dt><code>-fdbg-cnt-list</code></dt>
<dd><a name="index-fdbg_002dcnt_002dlist"></a>
<p>Print the name and the counter upper bound for all debug counters.
</p>

</dd>
<dt><code>-fdbg-cnt=<var>counter-value-list</var></code></dt>
<dd><a name="index-fdbg_002dcnt"></a>
<p>Set the internal debug counter upper bound.  <var>counter-value-list</var>
is a comma-separated list of <var>name</var>:<var>value</var> pairs
which sets the upper bound of each debug counter <var>name</var> to <var>value</var>.
All debug counters have the initial upper bound of <code>UINT_MAX</code>;
thus <code>dbg_cnt</code> returns true always unless the upper bound
is set by this option.
For example, with <samp>-fdbg-cnt=dce:10,tail_call:0</samp>,
<code>dbg_cnt(dce)</code> returns true only for first 10 invocations.
</p>
</dd>
<dt><code>-print-file-name=<var>library</var></code></dt>
<dd><a name="index-print_002dfile_002dname"></a>
<p>Print the full absolute name of the library file <var>library</var> that
would be used when linking&mdash;and don&rsquo;t do anything else.  With this
option, GCC does not compile or link anything; it just prints the
file name.
</p>
</dd>
<dt><code>-print-multi-directory</code></dt>
<dd><a name="index-print_002dmulti_002ddirectory"></a>
<p>Print the directory name corresponding to the multilib selected by any
other switches present in the command line.  This directory is supposed
to exist in <code>GCC_EXEC_PREFIX</code>.
</p>
</dd>
<dt><code>-print-multi-lib</code></dt>
<dd><a name="index-print_002dmulti_002dlib"></a>
<p>Print the mapping from multilib directory names to compiler switches
that enable them.  The directory name is separated from the switches by
&lsquo;<samp>;</samp>&rsquo;, and each switch starts with an &lsquo;<samp>@</samp>&rsquo; instead of the
&lsquo;<samp>-</samp>&rsquo;, without spaces between multiple switches.  This is supposed to
ease shell processing.
</p>
</dd>
<dt><code>-print-multi-os-directory</code></dt>
<dd><a name="index-print_002dmulti_002dos_002ddirectory"></a>
<p>Print the path to OS libraries for the selected
multilib, relative to some <samp>lib</samp> subdirectory.  If OS libraries are
present in the <samp>lib</samp> subdirectory and no multilibs are used, this is
usually just <samp>.</samp>, if OS libraries are present in <samp>lib<var>suffix</var></samp>
sibling directories this prints e.g. <samp>../lib64</samp>, <samp>../lib</samp> or
<samp>../lib32</samp>, or if OS libraries are present in <samp>lib/<var>subdir</var></samp>
subdirectories it prints e.g. <samp>amd64</samp>, <samp>sparcv9</samp> or <samp>ev6</samp>.
</p>
</dd>
<dt><code>-print-multiarch</code></dt>
<dd><a name="index-print_002dmultiarch"></a>
<p>Print the path to OS libraries for the selected multiarch,
relative to some <samp>lib</samp> subdirectory.
</p>
</dd>
<dt><code>-print-prog-name=<var>program</var></code></dt>
<dd><a name="index-print_002dprog_002dname"></a>
<p>Like <samp>-print-file-name</samp>, but searches for a program such as <code>cpp</code>.
</p>
</dd>
<dt><code>-print-libgcc-file-name</code></dt>
<dd><a name="index-print_002dlibgcc_002dfile_002dname"></a>
<p>Same as <samp>-print-file-name=libgcc.a</samp>.
</p>
<p>This is useful when you use <samp>-nostdlib</samp> or <samp>-nodefaultlibs</samp>
but you do want to link with <samp>libgcc.a</samp>.  You can do:
</p>
<div class="smallexample">
<pre class="smallexample">gcc -nostdlib <var>files</var>&hellip; `gcc -print-libgcc-file-name`
</pre></div>

</dd>
<dt><code>-print-search-dirs</code></dt>
<dd><a name="index-print_002dsearch_002ddirs"></a>
<p>Print the name of the configured installation directory and a list of
program and library directories <code>gcc</code> searches&mdash;and don&rsquo;t do anything else.
</p>
<p>This is useful when <code>gcc</code> prints the error message
&lsquo;<samp>installation problem, cannot exec cpp0: No such file or directory</samp>&rsquo;.
To resolve this you either need to put <samp>cpp0</samp> and the other compiler
components where <code>gcc</code> expects to find them, or you can set the environment
variable <code>GCC_EXEC_PREFIX</code> to the directory where you installed them.
Don&rsquo;t forget the trailing &lsquo;<samp>/</samp>&rsquo;.
See <a href="Environment-Variables.html#Environment-Variables">Environment Variables</a>.
</p>
</dd>
<dt><code>-print-sysroot</code></dt>
<dd><a name="index-print_002dsysroot"></a>
<p>Print the target sysroot directory that is used during
compilation.  This is the target sysroot specified either at configure
time or using the <samp>--sysroot</samp> option, possibly with an extra
suffix that depends on compilation options.  If no target sysroot is
specified, the option prints nothing.
</p>
</dd>
<dt><code>-print-sysroot-headers-suffix</code></dt>
<dd><a name="index-print_002dsysroot_002dheaders_002dsuffix"></a>
<p>Print the suffix added to the target sysroot when searching for
headers, or give an error if the compiler is not configured with such
a suffix&mdash;and don&rsquo;t do anything else.
</p>
</dd>
<dt><code>-dumpmachine</code></dt>
<dd><a name="index-dumpmachine"></a>
<p>Print the compiler&rsquo;s target machine (for example,
&lsquo;<samp>i686-pc-linux-gnu</samp>&rsquo;)&mdash;and don&rsquo;t do anything else.
</p>
</dd>
<dt><code>-dumpversion</code></dt>
<dd><a name="index-dumpversion"></a>
<p>Print the compiler version (for example, <code>3.0</code>)&mdash;and don&rsquo;t do
anything else.
</p>
</dd>
<dt><code>-dumpspecs</code></dt>
<dd><a name="index-dumpspecs"></a>
<p>Print the compiler&rsquo;s built-in specs&mdash;and don&rsquo;t do anything else.  (This
is used when GCC itself is being built.)  See <a href="Spec-Files.html#Spec-Files">Spec Files</a>.
</p></dd>
</dl>

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